The present invention relates generally to pump motors, and more particularly to cable connector assemblies that are used to provide a connection between exterior electrical cables and internal circuitry of the motor.
In the sewage treatment industry, pumps are used in many applications. Some applications are “dry”, meaning that the pump is not submerged in the liquid it is pumping, while other applications are “wet”, meaning that all or a large portion of the pump and its motor are submerged. These pumps are driven by electrical motors powered by electricity. Cables must be run to the motors to provide electrical power to the motors, and these cables are usually passed through an opening in the pump or motor housing. The opening has a cap or cover member that closes the opening and the cables also pass through an opening in the cap. It is important to provide an effective seal between the cables and the cap in order to prevent liquid from entering the interior of the motor, either under pressure or by wicking through the cable.
The pump industry commonly utilizes two different designs for such cable connectors. In one design, the interior space of the cap is “potted”, meaning it is filled with epoxy or some other sealant and in another design, rubber or flexible grommets are compressed to form a seal around the cables in the cap. Both designs have their problems. In the former design, a large amount of epoxy is used and this increases the cost of the connector assembly. Such a design is not suitable for repair in the actual operating environment of the motor, for all of the epoxy needs to be removed form the interior space of the cap. In the latter design, one or more rubber grommets, or bushings, are used to both seal the cables and retain the cables in place by applying pressure on the exterior of the cables. Such an assembly needs to be assembled each time the cable is connected to the motor. This is time-consuming and increases the labor cost of this design, and this exposure of the cable makes it susceptible to damage
One embodiment of the present invention is directed to a cable housing-connector assembly that overcomes the aforementioned disadvantages
Pump motors may be cooled in a variety of different ways. One way that is used for cooling a pump motor involves the use of a cooling liquid being pumped to cool the pump motor. This is accomplished by manufacturing a torturous path in the sidewalls of a motor casing to create many fluid cooling channels. This is expensive and sediments and other particulates in the pumped fluid may accumulate in the cooling channels and clog them to the point where the flow of cooling liquid is stopped in some areas, thereby resulting in localized hot spots. Servicing such a motor construction requires that the motor be removed from service and brought to a repair facility.
Another motor cooling construction involves mounting a fan or blower above the motor so that it forces air down and across the motor. This construction has a lower reliability because it requires a separate blower motor and the blower motor needs servicing if the pump area becomes flooded and the blower motor becomes flooded. For explosion-proof reliability the blower motor must also be made explosion-proof.
Yet another manner of motor cooling, that is used often in the field of dry-pit pumping, is one in which the cooling fan is connected to and above the motor shaft. Some problems are inherent in this design in that the interconnection between the blower fan and the motor creates a potential point of leakage, and the motor must be stopped when the motor becomes flooded in order to protect both the motor and the fan.
Another embodiment of the present invention presents a solution to the aforementioned problems in the form of a motor construction where the fan is coupled to the motor shaft in a manner that substantially eliminates the need for concern over leaks and in a manner that stops rotation of the fan when the motor is flooded without placing a large drive load on the motor.